The present invention relates to motor vehicle wheel hub assemblies, and more particularly to coupling assemblies for connecting constant velocity joints and a hub bearing units.
US Patent Application No. 2002/0070506 A1 and U.S. Pat. No. 6,354,952 each disclose arrangements in which the hub of the wheel receives the driving torque from the bell of the constant velocity joint through a straight splined coupling. To this end, fixed on the hub is a ring with an axial outer toothing/splines that is telescopically inserted in a tubular projection with an inner axial toothing of the outer part or “bell” of the constant velocity joint. The toothed ring and the tubular projection are both provided with a respective circular groove in which an elastic, open ring (or circlip or Seeger ring) is fitted in order to axially lock the hub to the joint.
The known arrangements as described above are generally effective, but have drawbacks, such as for example, insufficient sealing. The elastic ring typically has two gripping arms at its ends that project through a slot formed at the axially outer end (or outboard end) of the joint bell. As shown in FIG. 5 of US 2002/0070506, a rubber sleeve may be provided to cover the slot, and thereby seal it. Such a sealing arrangement often permits water or other fluids to penetrate, especially through the slot formed at the end of the joint bell, into the splined interface zone. Rust formed at the interface of the splined coupling renders the disassembling operation of the hub-bearing unit from the constant velocity joint particularly difficult, besides shortening the life of these members.
Further, a conventional straight splined coupling has the drawback of a relatively high level of noise that can be heard when the vehicle is put into reverse, due to to the circumferential or angular play between the splines on the bell of the constant velocity joint and the driving ring fixed on the hub.